Selective audio relay



Dec. 30, 1952 P. E. FISCHLER 2,623,966

SELECTIVE AUDIO RELAY Filed April 1, 1949 INVENTOR. PAUL E. FISCH LER ATTORNEYS Patented Dec. 30, 1952 UNITED STATES PATENT OFFICE SELECTIVE AUDIO RELAY Paul Fiscliler, Buffalo, N. Y., as'sig'nor of onc half to John Nathanson, Buffalo, N: Y.

Application April 1, 1949, Serial No. 84,909

3 Claims. 1

This invention relates to a selective audio relay which may be tuned to operate at any frequency within the audio spectrum and more specifically to an improved device of this nature'which has advantages over the device disclosed in the copending application, Serial Number 24,780, filed May 3, 1948, and entitled Tuned Audio Relay.

An object of the invention is to provide a relay of the class described in which leakage paths in the magnetic circuit are reduced to a minimum and the magnetic flux is concentrated at one point, thereby improving the efliciency of the relay.

Another object is the provision of a selective audio relay having improved armature suspension.

A further object is to provide in a relay of the class described a method of assembling the two inductors of the relay in such a manner that their lumped inductance may be accurately adjusted to any operating frequency, thereby affording a means of compensating for production variations in the inductors and capacitors and also allowing the use of one set of inductors for tuning over a narrow band of frequencies.

dust cover [3 cut away to show the face of the relay;

Figure 3 is a view of the relay with the dust cover cut away to show the reverse side of the relay;

Figure 4 is a top view of the relay with the dust cover removed and with the switch and condenser assemblies omitted to clearly show the assembly of the magnetic circuit to the mounting plate; and

Figure 5 is an enlarged view showing the method of armature suspension and adjustment.

Since this device is designed to operate as part of a series or parallel resonant circuit, it is essential that the values of inductance and capacitance at the operating frequency be selected and adjusted to provide proper current or voltage distribution throughout the circuit. For this reason it is necessary to compute the L-C ratio at a given frequency so that the impedance of the circuit at resonance'is' essentially the D. C. resistance of the circuit components. (Maximum circuit Q.) These ratios are shown in the following table.

Values of L, C, R, Z1 and Q for frequencies from 200 to 1800 O. P. S.

Freq 200 300 400 500 600 700 800 900 1,000 1,200 1,400 1,500 1,600 1,800

L 1.04 1.18 1.34 1.40 .351 .353 .357 .362 .369 .211 .214 .219 .144 .149 C .00 .24 .118 .074 .20 .146 .110 .086 .068 .087 .06 .052 .068 .052 R 400 100 75 Z1 2M 500 300 Q 3.3 I 5.6 l 8.4 11.0 13 I 15.5 I 18 I 21 23 21 25 27.5 29 33.6

Another object of the invention is the provision of a plug-in relay of the type described having ample space for mounting of capacitors either singly or in parallel, thereby allowing the use of readibly purchasable stock capacitors.

Other objects and advantages willbe apparent from the following specification and the accompanying drawings in which by way of illustration a preferred embodiment of the device is disclosed.

It will be understood, however, that the invention is not limited to this disclosure, as many modifications and changes'therein may be made, the invention being as defined by the appended claims.

Referring to the drawings:

Figure 1 is a bottom view of the relay showing the Bakelite base plate and connecting plug thereof Figure 2 is a side view of the relay with the In practice values of Rand Z1 are maintained for several frequencies. (This is shown by arrows on chart.)

L is given in henries C is given in microfarads R is given in ohms Z1 is given in ohms QzFigure' of merit Referring to Fig. 1 it will be seen that the relay has a base plate [0 on which is mounted a standard type i-prong connector plug 3%. The base plate is secured to the mounting plate i l by means of screws II and I2 and is provided with a dust cover or cap 13 which isshown in Figs. 2 and 3 as cut away to show the two sides of the relay.

The mounting plate [4 is preferably made of brass and is secured to the Bakelite base plate 19 by means of the screws H and I2. The inductors I5, I6 suitably wound for any desired frequency are mounted on the laminated iron core I! which is tightly clamped between brass plates l8, [9 by means of the screws 20, 2! which also assemble the magnetic circuit parts to the mounting plate l4.

Two inductors l5, it are employed to obtain the total required inductance, the value of which may be varied over a narrow band of frequencies by connecting the coils-series-aiding or seriesbucking and also by varying the spacing 43 between the coils to change their mutual inductance.

The space 43 can be varied by having the coils a pressed fit on their iron core and by moving one relative to the other, or the coils can be a sliding fit and can be relatively moved until the proper adjustment is obtained, whereupon some quickdrying cement is placed in the space 43 between the coils and the core to hold the coils fixed in the desired position, or they can be fixed to the core in any other manner.

The brass plates [8, [9 have extensions 22, 22a at one end as shown to provide space for tapped holes to accommodate case hardened pivot screws 23.

A slot 25 is cut in from one edge of the plates to the tapped holes to provide means for applying tension to the threads of the pivot screws to hold them securely without the aid of jam nuts.

The soft iron armature 26 is assembled by holding the vertical portion tightly against the poles of the iron core and adjusting the pivot screws to firmly engage the edges of the armature, and this manner of assembly eliminates the possibility of a reluctance gap at the pivoting point thereby minimizing magnetic leak-age and con centrating the greatest magnetic flux at the opposite pole.

As the pivot screws are sharply pointed, the armature is delicately poised to move freely, and yet is securely held in operating position at all times.

An insulating plate 24 is assembled to the mounting plate I4 by means of screws Ma and Mb and carries the contact spring 21, spring tensioning screw 28 and adjustable contact screw 29;

Movement of the armature 26 is conveyed to the contact spring 21 by means of an insulating pin 30. The adjustment of the armature and the switch just described is accomplished by setting the-air gap between the long leg 26a of armature 26 and the pole face 3| of the iron core by means of adjusting screw 32 and spring tensioning screw 28 to hold the armature lightly against screw 32, and then adjusting the screw 29 to allow the switch contact to close as the armature is attracted to the pole face 3|.

The form of switch above described affords greater accuracy of adjustment with a resultant increase in relay sensitivity as compared with ordinary types of commercial switches used on previous devices, as it has been found that ordinary types of switches suchas that shown in the co-pending application before mentioned cannot be obtained in quantities to meet the uniform pressure and over-travel specifications necessary in a device of this character.

The switch herein described is merely illustrative of any spring-biased device operable to open or close contacts or to switch electrical circuits in any manner; or this device may be Sylphon bellows or other pressure varying or responsive device adapted to control a valve or the like.

As such devices are of numerous types and are all well known, same are not described in detail as obviously any biased device can be used, de pending on the function desired.

It will also be obvious that the pressure of the contact spring 21 or other equivalent member is communicated to the armature 28 and aids in the tuning of the relay.

In Fig. 3, the dust cover [3 is cut away to show the reverse side of the relay. The capacitor 33 is secured to the mounting plate It in any suitable manner and may be held thereto by means of the insulated lead wires 34, 35 which pass through holes in the mounting to the opposite side of the assembly.

In Fig. 4 the dust cover I3 is removed and the switch and condenser assemblies omitted to clearly show the assembly of the magnetic circuit to the mounting plate Hi. The excess space shown has been provided to allow assembly of a vertical bracket to the base plate [3 upon which the condensers may be mounted when two or more parallel connected capacitors or condensers are required to tune to low frequency.

Figure 5 is an enlarged view showing the details of the armature suspension and adjustment previously described and is self-explanatory.

The electrical circuits not shown are very simple in that the inductors and condensers are merely connected in series. This may be acco l-- plished by connecting the condenser lead 3 3 to a small pin it on plug 35. The latter would connect to the line or circuit in which the relay is used, the other side of said circuit would connect to the small pin 5 which connects to terminal 31 on one of the inductors iii.

The other terminal 38 on this inductor is connected to a terminal 3% on the second inductor [6 (the inductors being connected series-aiding or bucking as required). The other terminal 56 on the second inductor i5 is connected to the second condenser lead 35, thus completing the internal circuit of the relay.

The internal circuit to the switch Or other spring biased device is made from the large pins 126, ii which connect to the terminals 61, 62 on contacts 2'! and screw 29.

What is claimed is:

1. In a tuned relay responsive to a predetermined frequency, a pair of windings; a U-shaped core comprising a plurality of laminations, said windings being mounted on one leg of said core and being relatively movable therealong to vary the predetermined frequency, the free ends of said core extending outwardly beyond the end of the outermost winding thereon, means extending transversely of the exposed leg of said core for securing said laminations together, an L-shaped armature one leg of which extends across the free ends of said core, the other leg of same extending along the exposed side of said core toward the closed end thereof, a support for said core, means carried by said support for movably securing said armature in rockable relation to said core, a contact spring overlying a portion of said armature to be actuated thereby, a contact member mounted on said support and adapted to cooperate with said contact spring, and means mounted on said support for adjusting said armature relative to said core.

2. The relay as claimed in claim 1 wherein said means for movably securing said armature to said core comprises pins extending through apertures in said armature and into said core whereby same is rockably supported thereon and in direct metallic contact therewith.

3. In a tuned audio relay responsive to a predetermined frequency, a base plate; a plate-like support mounted on said plate and extending in a plane perpendicular thereto: an alternating current electromagnet secured to the flat side of said support and comprising a U-shaped core of a plurality of laminations; a pair of windings mounted on one leg of said core and being relatively movable therealong to vary the predetermined frequency; the free ends of said core extending outwardly beyond the outermost winding thereon; an L-shaped armature one leg of which extends across the free ends of said core, the other leg of said armature extending along the exposed end of said core toward said base plate; means carried on said plate-like support for movably securing said armature in rockable relation to said core; adjusting means mounted on said platelike support adapted to contact said armature to adjust the same where it overlies the free ends of said core; and a control device mounted on said plate-like support engaged by said armature for operation thereby.

PAUL E. FISCHLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 130,048 Hicks et a1. July 30, 1872 220,333 Bates Oct. 7, 1879 289,285 Maloney Nov. 27, 1883 1,647,474 Seymour Nov. 1, 1927 1,970,383 Ivluehter Aug. 14, 1934 2,938,297 Ketcnam Apr. 21, 1936 2,137,818 Wagar Nov. 22, 1938 2,148,553 Rypinski Dec. 20, 1938 2,430,990 Moore Nov. 18, 1947 2,441,137 Anthony May 11, 1948 2,465,198 Christianscn Mar. 22, 1949 2,476,419 Koenig July 19, 1949 2,496,742 Neild Feb. 7, 1950 FOREIGN PATENTS Number Country Date 562,461 England July 3, 1944 

